This competitive revision application is submitted in response to notice NOT-OD-10-032, titled "NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications (R01, R03, R15, R21, R21/R33, and R37) through the NIH Basic Behavioral and Social Science Opportunity Network (OppNet)". The parent R03 developed a new analysis tool for relating confidence judgments (e.g., "I'm certain I was correct") to memory responses (e.g., "I believe I saw that face before"). Because confidence judgments are given separately from memory responses, there may be 1) measurement error in the confidence judgment;2) measurement error in the memory response;or 3) these two behavioral responses might be based on different kinds of information. The analysis tool uses patterns of data across two or more conditions to separately quantify these three mechanisms, each of which can lead to confidence judgments that appear to be inaccurate. This revision seeks to advance this analysis tool through its application to confidence judgments of perceptual responses (e.g., "that's the face I just got a brief glimpse of"). A preliminary study suggests that confidence judgments may act in a fundamentally different manner for perception as compared to memory. As expected under the assumption that confidence judgments introduce an additional source of measurement error, confidence judgments of memory were found to be less accurate than suggested by forced-choice memory decisions. However, the opposite was found for confidence judgments of perception. In its original form, the analysis tool cannot account for this pattern of data. Instead, these results suggest that the measurement error associated with perceptual confidence is coupled to the error of perceptual information. Besides validating this extension of the analysis tool through simulation studies, three behavioral experiments will test predictions of this account. These experiments will investigate the interplay between memory and perception as it relates to confidence judgments. In particular, these experiments will ascertain whether confidence judgments of perception use long-term memorial information (e.g., "that's a familiar face") to optimally adjust the reported level of confidence. PUBLIC HEALTH RELEVANCE: Perceptual disorders are often measured through the inability to rapidly identify visual objects such as faces or words, but these deficits may reflect a change in the certainty associated with potential responses rather than a deficit in the underlying perceptual information. By collecting confidence judgments as well as perceptual identification responses, the proposed work will develop a set of measurement tools that can differentiate between the possible sources of perceptual deficits. These measurement tools will be relevant to differential diagnoses of perceptual disorders as well as clinical therapies designed to alleviate perceptual difficulty.